Congenital long QT syndrome is a group of genetically transmitted disorders characterized by abnormal cardiac repolarization resulting in QT interval prolongation that predisposes patients to the acute onset of ventricular arrhythmias, most notably torsades de pointes, which may cause syncope or sudden cardiac death. Long QT syndrome is usually transmitted in an autosomal dominant pattern. Diagnosis remains challenging, as roughly 40% of patients with genotype-positive LQTS do not demonstrate QT prolongation on resting ECG. Clinical manifestations are heterogenous and include presyncope, syncope, aborted cardiac arrest, cardiac arrest, and sudden cardiac death but many patients are completely asymptomatic. Many of the medications administered during an anesthetic affect the QT interval. Additionally, patients with long QT syndrome may require the placement of pacemakers, implantable cardioverter-defibrillators and/or cardiovascular implantable electronic devices. This chapter discusses the perioperative management of patients with long QT syndrome and appropriate management of implanted devices during the perioperative period.